The present invention relates to novel pyrene compounds, a method for manufacturing them and an electrophotographic photoreceptor containing the pyrene compounds.
A study of photoconductive materials has recently been made actively, and the materials have been applied as a photoelectric conversion element such as a solar battery and an image sensor as well as an electrophotographic photoreceptor. Heretofore, inorganic materials have mainly been used for photoconductive materials. For example, an inorganic photoreceptor provided with a light-sensitive layer containing, as the main component, inorganic photoconductive materials such as selenium, zinc oxide or cadmium sulfide has been used widely. Such inorganic photoreceptor, however, has not necessarily been satisfactory on the points of characteristics required as an electrophotographic photoreceptor to be used in a copying machine such as photographic sensitivity, thermal stability, moisture resistance and durability. For example, the characteristic of selenium as an electrophotographic photoreceptor is easily deteriorated because the selenium is crystallized by heat or by finger print contamination. An electrophotographic photoreceptor employing cadmium sulfide, on the other hand, is inferior on the points of moisture resistance and durability, and an electrophotographic photoreceptor employing zinc oxide is also problematic on the point of durability. Furthermore, in recent years wherein environmental matters are taken seriously, an electrophotographic photoreceptor employing selenium or cadmium sulfide has disadvantages that restriction on manufacturing and handling thereof is strict on the point of its toxicity.
For improving the disadvantages of inorganic photoconductive materials, various organic photoconductive materials have drawn an attention to try to use it for a light-sensitive layer of an electrophotographic photoreceptor, and the study to use it have been conducted actively in recent years. For example, an organic photoreceptor provided with a light-sensitive layer containing polyvinylcarbazole and trinitrofluorenone is disclosed in Japanese Patent Examined Publication No. 10496/1975. However, this organic photoreceptor is not satisfactory on the points of photographic sensitivity and durability. Therefore, there has been developed an electrophotographic photoreceptor of a separated function type in which a carrier-generating function is carried out by one substance and a carrier-transport function is carried out by the other substance. In the field of such electrophotographic photoreceptor, it is expected to obtain an organic photoreceptor having high sensitivity and high durability, because desired characteristics are easily obtained due to wide selection of each material.
As a carrier-generating substance and a carrier-transport substance for such electrophotographic photoreceptor of a separated function type, there have been proposed various organic compounds. As a carrier-generating substance, photoconductive substances such as polycyclic quinone compounds represented by dibromoansanthrone, pyrylium compounds, eutectic crystal complexes of the pyrylium compounds, squarilium compounds, phthalocyanine compounds and azo compounds have been put to practical use.
For example, as an electrophotographic photoreceptor containing polycyclic quinone compounds in a light-sensitive layer, Japanese Patent Publication Open to Public Inspection Nos. 76933/1974, 75042/1975 and 180955/1988 (hereinafter referred to as Japanese Patent O.P.I. Publication) are known. However, these compounds are not necessarily satisfactory on the points of characteristics such as sensitivity or the like, and a range for selection of carrier-transport substances is limited, the compounds does not satisfy sufficiently the requirements of electrophotographic process in a wide range.